BDELLOID ROTIFERA OF SOUTH AFRICA. 81 



transverse rows of tiles or overlapping plates on tlie trunk. Ros- 

 trum very stout. Antenna short, about one-third neck width. 

 Teeth, 3/4. Foot of four segments. Spurs short, sharp with 

 wide, flat interspace. Corona slightly wider than collar. Upper 

 lip has a broad front margin with a gentle indentation. Size, 

 1/lOOth inch. 



This little animal has a most extraordinary yet attractive 

 appearance. Viewed from the front and looking downwards, 

 the trunk seems protected with five transverse rows of tile-like 

 parts overlapping posteriorly. These parts are not excrescences, 

 or foreign to the trunk as in M. incrassata, but the true skin, 

 ridged and bent into these little oblongs, as is made apparent 

 by the alteration of their shape with every movement of the 

 body, especially when creeping. If looked at sideways, when the 

 animal is feeding horizontally, the dorsal crests and hollows can 

 be seen, and it can be noticed also that the borders of the crests, 

 instead of curving down gradually to form the hollows, suddenly 

 bend straight down or even backwards, causing the appearance, 

 already mentioned, of tiles overlapping. The top edges or rims 

 of the ridges are easily focused, and are of a glaucous green colour, 

 contrasting sharply with the grey between. These loops appear 

 also on the rump with a little variation, but of a permanent 

 character, and are triple in the anal segment. 



M. macmillani is a fast creeper, with a short glide or slither 

 with each step ; and it feeds freely and quietly. 



The rostrum is stout with a double lamella which stands out 

 clearly. The antenna is short and exceptionally broad at the 

 base. The jaws are not very large, are winged and have three 

 teeth in the one and four in the other. When the animal is creep- 

 ing, the neck shows quite a distinctive shape. There is a gradual 

 curve from the rostral to the dental segment, the narrowest part 

 being about half-way between. 



The rump seems to have three divisions, but not very markedly 

 so, and it is somewhat doubtful what belongs to the anal and what 

 to the pre- anal segments, though probably the anal is very large 

 and consists of two of these apparent divisions. The intestine 

 and contractile vesicle are both large. The spurs are short with 

 a wide, flat interspace. There is a short foot of four segments, 

 and on the last segment there is a ring expansion, but not large 

 enough to show outside the ankle, as in M. petulans. 

 JouRN. Q. M. C, Series II.— No. 78. 6 



